In the art of designing various objects or structures over which fluid media flow, it is often desirable to impart to such objects or structures a special shape or configuration which causes the fluid media to flow in such a manner as to attain a particular result.
One common and well-known end sought to be attained by specially shaping or forming objects over which fluid media flow, is to minimize the resistance and/or friction losses between the objects and the fluid media, whereby less energy is required to move the media relative to the objects or vice-versa. Such shaping or forming of objects is commonly referred to as "streamlining", and is widely practiced in the designing of aircraft, automobiles, and other objects and structures which move through the air when in use.
Another common and well-known end sought to be attained by special shaping and forming of solid structures, such as aircraft wings, is the attaining of airfoil shapes which establish most effective and efficient pressure differentials across the structures or wings, as they move in and relative to the air under predetermined operating conditions.
In the past, to determine how a fluid medium such as air flows about a solid object such as a wing, it has been common practice to fix a multiplicity of telltale streamers onto and throughout those portions of the wing surfaces which are to be evaluated or studied, and to thereafter effect desired movement of air over those surfaces, as by moving air over the wing in wind tunnel testing.
The same or analogous procedures are followed when testing and studying automobile bodies, the shapes of air ducts and most other structures and parts where an understanding of the dynamic relationship of the structures with a fluid medium is sought.
Prior to my invention, telltales have consisted of individual, elongate pieces of flexible material such as thread, string, ribbon and in some instance strips of paper, which have been manually arranged, one at a time, about the surfaces of the object or structure to be studied and which have had one end thereof secured to the related surfaces by means of glue or by pieces of pressure sensitive adhesive tape, whereby the pieces of material establish streamers at or adjacent to the surfaces.
The foregoing practice is extremely slow and tedious work and is such that unless great and special care and skill is practiced, the effectiveness of the study to be made cannot be assured.
Also, in carrying out the aforementioned procedure of affixing individual telltale streamers to surfaces of objects and structures, it is difficult to maintain all of the streamers of equal length; establish uniform spacing between related streamers; or assure that the streamers will not part or be pulled free from their related surfaces when worked upon by a fluid medium.